1. FIELD OF THE INVENTION
The invention is related to a starter drive for internal combustion engines and in particular to a starter drive having increased impact resistance.
2. DESCRIPTION OF THE PRIOR ART
The invention is an improvement of the starter drive such as those taught by Digby in U.S. Pat. No. 3,263,509 and U.S. Pat. No. 3,714,834. These starter drives are slidably disposed on a power shaft connected to a starter motor and are axially displaced along the power shaft to engage a pinion gear with the ring gear of the engine. The starter drives taught by Digby contain an indexing mechanism which rotates the pinion gear in the event that the teeth of the pinion gear fail to mesh with the teeth of the ring gear of the engine as the starter drive is displaced. The indexing mechanism includes a spring or resilient bumper which absorbs the shock when the pinion gear abuts rather than engages the ring gear.
In an alternate arrangement taught by Johnson in U.S. Pat. No. 3,915,020, a bumper spring is applied between the external housing and a drive clutch member which permits the pinion gear to be indexed when it abuts rather than engages the ring gear. Johnson also provides a multi-piece external housing in which two concentric housing members are biased toward each other by an annular resilient member. This resilient member partially absorbs the force resulting from the axial displacement of the clutch and the pinion members by the bumper spring when the pinion gear is indexed into alignment with the ring gear of the engine.